This invention relates to intraluminal grafts for repairing defects in arteries and other lumens within the body. More particularly, the present invention relates to modular systems for forming endovascular grafts for implantation and assembly in-situ for repairing defective body lumens.
An abdominal aortic aneurysm is a sac caused by an abnormal dilation of the wall of the aorta as it passes through the abdomen. The aorta is the main artery of the body, supplying blood to various organs and parts of the body. It arises from the left ventricle of the heart, passes upward, bends over and passes down through the thorax and through the abdomen, and finally divides into the two iliac arteries which supply blood to the pelvis and lower extremities. The aneurysm ordinarily occurs in the portion of the aorta below the kidneys. When left untreated, the aneurysm will eventually cause the sac to rupture with ensuing fatal hemorrhaging in a very short time. The repair of abdominal aortic aneurysms has typically required major abdominal surgery in which the diseased and aneurysmal segment of the aorta is removed and replaced with a prosthetic device, such as a synthetic graft.
As with all major surgeries, there are many disadvantages to the foregoing surgical technique, the foremost of which is the high mortality and morbidity rate associated with surgical intervention of this magnitude. Other disadvantages of conventional surgical repair include the extensive recovery period associated with such surgery; difficulties in suturing the graft to the aorta; the loss of the existing thrombosis to support and reinforce the graft; the unsuitability of the surgery for many patients, particularly older patients exhibiting co-morbid conditions; and the problems associated with performing the surgical procedure on an emergency basis after the aneurysm has already ruptured.
In view of the foregoing disadvantages of conventional surgical repair techniques, techniques have been developed for repairing abdominal aortic aneurysms by intraluminally delivering an aortic graft to the aneurysm site through the use of a catheter based delivery system, and securing the graft within the aorta using an expandable stent. Since the first documented clinical application of this technique, the technique has gained more widespread recognition and is being used more commonly. As vascular surgeons have become more experienced with this endovascular technique, however, certain problems have been encountered.
One problem has been the difficult nature of the procedure. Another problem has been the kinking and/or twisting of the graft both during and after the graft has been implanted. Still other problems relate to the need for accurate preoperative measurements to be made on the morphology of the aneurysm and the surrounding arterial structure, including the length of the aneurysm, the infrarenal aortic length and diameter, the length and diameter of the aorta between the aneurysm and the iliacs, the diameter of the iliacs, and the angle between the iliacs and the aorta. The difficulty in making these measurements accurately and the wide variations in these measurements among patients mandates that the bifurcated grafts be available in a wide range of sizes and configurations.
Endovascular repair of the abdominal aortic aneurysm (AAA) using a stent/graft prosthesis that is assembled in-situ is gaining acceptance due to reduced surgical complications, and providing an alternative solution for patients that cannot be treated surgically. However, the large degree of variation in the geometry and dimensions of vascular anatomy from patient to patient poses a problem for the physician in selecting a device, and for the manufacturer in the number of parts required in inventory.
Current modular bifurcated systems are often designed to specific trunk-to-limb diameter ratios (e.g. a stent with a 24 mm trunk will have 12 mm limbs) and most designs have one or both limb(s) pre-attached to the trunk. Also, current modular bifurcated stents are often designed with a limited amount of adjustability in length. If a two-piece system already has one limb attached to the trunk, there is a fixed length for one side of the device. Furthermore, the contralateral limb (or each limb in a three-piece device) typically has a narrow insertion range. These approaches limit the choices that a physician has in selecting a device for a given patient, and potentially excludes patients with abnormal vasculature.
Therefore, there exists a need for a bifurcated graft and an implantation method which will overcome the foregoing deficiencies of the prior art. More particularly, there exists a need for a modular graft system which will more accurately accommodate the widely varying arterial sizes in patients, as well as the other size considerations now faced by the surgeon. The present invention addresses these and other needs.